Projects / Programmes
Nanostructured cathodes for lithium sulphur batteries
| Code |
Science |
Field |
Subfield |
| 2.04.01 |
Engineering sciences and technologies |
Materials science and technology |
Inorganic nonmetallic materials |
| Code |
Science |
Field |
| P401 |
Natural sciences and mathematics |
Electrochemistry |
| Code |
Science |
Field |
| 2.05 |
Engineering and Technology |
Materials engineering |
Energy storage, lithium-sulfur batteries, nanoarchitecture, sensors, spectroscopic methods, electroanalytical methods
Researchers (9)
Organisations (2)
Abstract
Sustainable development and the demand for the rechargeable batteries with a higher energy density make lithium–sulfur (Li-S) batteries attractive candidates. Li-S batteries poses two major advantages: a high energy density (2500 Whkg-1, or 2800Whl-1) and a low price (due to low price of sulfur). At present, the practical use is faced with two major problems: (i) a low intrinsic conductivity of sulfur and polysulfides and (ii) loss of active materials due to solubility of the intermediate products in the commonly used electrolytes. Generally, the low intrinsic conductivity can be overcome using improved electronic wiring. The occurrence of soluble polysulfides is reflected as a loss of the active material during the cycling (observed as a capacity fading) and additionally soluble polysulfides are responsible for so called “shuttle mechanism” which lowers the energy efficiency (observed as an overcharge). With an aim to have stable capacity retention with a good cycling efficiency it is important to find a suitable electrochemical environment for the lithium – sulfur batteries. Among all solutions published so far in the literature, none of them shows applicable electrochemical properties (cycling stability with high energy efficiency). Additionally, in most cases the slightly improved cycling stability is not well explained/understood. An overview of the recent advances shows that the physical properties of the hosting matrix for sulfur impregnation needs to be tailored following appropriate decoration or grafting of the surface with modifiers so that weak bonding between the host and polysulfides that are dissolved in the electrolyte are possible.
Within scope of results mentioned above, the project will focus on the design and tailoring of host structures with controlled porosity and tailored chemical properties. More specifically, we will focus on the optimizing the:
Impact of the surface properties (acidity, hydrophobicity, surface defects,…) of additives/coatings on the polysulfide shuttle mechanism;
Influence of surface area (BET vs. capacity, cycling stability);
Impact of the porosity (pore size, pore volume, shape of pores, type of porosity,...);
Impact of the type of additives (electron conductive additive, semi-conductor, type of ceramics, ...);
Ratio between sulfur and the additive(s) (normalized per selected additive property – like surface area, pore volume, pore size).
To understand the impact of different physical and chemical properties on the stability and energetic efficiency we plan to use in-situ analytical characterization methods which will be used for the identification of soluble polysulfides and which will help us to understand the mechanism of Li-S battery operation in different chemical environments. Within this, we plan to develop and use several different in-situ analytical techniques developed in the collaboration with partners in the project with a final goal to determine composition of Li-S battery with stable cycling properties. In this project we will use already demonstrated electrochemical analytical methods, spectroscopic analytical methods based on UV-Vis and Raman spectroscopy and methods based on low energy physics spectroscopies (X-ray absorption and Mössbauer spectroscopy). Use of XAS has been granted as two years project at Synchtron Elettra in Trieste (all together 360 hours).
Host structures will be developed in the collaboration with Max-Planck institute for colloid chemistry. Tailoring of the surface properties will be part of joint interest with the largest laboratory in Europe for Lithium batteries in Amiens (France).
We assume that with systematic work and with collaboration which goes behind the scope of this project we can demonstrate a stable Li-S battery behavior (capacity fading below 0.025% per cycle) and energy density at least 400Wh/kg.
Significance for science
Unequivocally project was important for the development of lithium sulphur batteries. The first indicator is the number of publications and the number of the invited lectures, which are the result of the project. One of the most significant achievements has been the development of analytical methods which have a great importance because they allow a better understanding of the introduction of new components in lithium sulphur batteries. Above all, the development and application of UV-Vis spectroscopy and X-ray absorption spectroscopy were very well accepted in the literature, which is reflected in large number of citations. In this project we have demonstrated the role of a numerous porous substrates. Gained knowledge was applied in HELIS project and used in the design of components for Li-S prototypes with a capacity of 5Ah, which are prepared within the project. Another important achievement is the development of fluorinated graphene oxide thin film on the separator. The patent application is in the process of granting of European patent and the work continues within HELIS project, where the chemically modified cellulose is currently in use and is intended to be used in prototypes within the HELIS project.
Significance for the country
Direct relevance for the development of Slovenia is enrichment of knowledge within the battery group at the Department of Materials Chemistry at the National Institute of Chemistry. This creates an environment that allows successful cooperation with many industrial partners in Slovenia (Pipistrel, TAB, EELS, ISKRA , Autoelektrika, Emrax, and others). Environmental requirements and increased use of renewable energy sources also brings increased usability of batteries that serve as intermediate energy storage systems. At the same time importance of the understanding of the various battery systems, which are developed within the group is growing. The development itself also indirectly influence on the development of Slovenia. One of the largest shares in Slovenian GDP is the cooperation with the automotive sector and it is this sector, which is increasingly focusing to the area of electro-mobility. Knowledge on the field of battery systems is very important for this sector. Undoubtedly, the future lies in the use of renewable energy sources, where the batteries will have an important role and accumulated knowledge in the group will be very important for the development of Slovenia in this field.
Most important scientific results
Annual report
2013,
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Annual report
2013,
2014,
2015,
final report
